Operational definitions used in study
| Training session | Team training that involved physical activity under the supervision of the coaching staff |
| Match | Competitive or friendly match against another team |
| Injury | Any physical complaint sustained by a player that resulted from a football match or football training and led to the player being unable to take full part in future football training or match play |
| Ankle injury | Injury to the tibiotalar and the inferior tibiofibular joints as well as the surrounding stabilising connective soft tissue (ie, joint capsules and ligaments) of these joints and the overlying skin |
| Slight/minimal injury | Injury causing 0–3 days lay-off |
| Mild injury | Injury causing 4–7 days lay-off |
| Moderate injury | Injury causing 8–28 days lay-off |
| Severe injury | Injury causing >28 days lay-off |
| Traumatic injury | Injury with sudden onset and known cause |
| Overuse injury | Injury with insidious onset and no known trauma |
| Reinjury | Injury of the same type and at the same site as an index injury occurring within 2 months after return to full participation from the index injury |
| Non-contact injury | Injury occurring without contact with another player or object |
| Dominant leg | Preferred kicking leg |
| Foul play | Violation of the laws of the game according to the match referee |
| Injury rate | Number of injuries per 1000 player hours ((Σ injuries/Σ exposure hours)×1000) |
| Injury burden | Number of lay-off days per 1000 player hours ((Σ lay-off days/Σ exposure hours)×1000) |